The AME has been consulted by the pilot, and gives him a sick note. His depression has returned. The airline will give him time off work to recover, and SHOULD NEVER LET HIM FLY AGAIN! So of course he will hide the news. Therefore,it is the duty of the AME, or his private physician, to inform the Company directly, as a matter of urgency.
But pilots who want to keep on flying, will avoid the medics altogether. Or find a medic who is too busy to notice. So who is going to be the whistleblower ?
It has to be his mates, his co-workers. Or his family. After this shocking event, perhaps friends and family would be willing to express concern to a doctor, any doctor, who should then have a legal duty to inform the airline.
Slats 11, who posted from Sidney at 13.22, has a good suggestion.
Is it possible, logistically, for an airline to schedule aircrew to work as a team on a REGULAR BASIS? A small group well acquainted with each other will soon spot when one of the team is not right.